In high voltage power MOS transistors, or in scaled down MOS transistors, breakdown of the gate oxide and gate oxide reliability becomes a concern. Higher electric fields in the oxide increase the incidence of tunneling of carriers from the channel into the gate oxide. These carriers slowly degrade the quality of the gate oxide, over time leading failure of the gate oxide. This effect is referred to as time dependent destructive breakdown.
Development in the area of protection circuits for the gate oxide of transistors in some environments have been developed. However, the development of protection circuits for the gate oxides of power MOS transistors in high voltage applications is still needed.